In the related art, when semiconductor components or flat panel displays are manufactured, a substrate processing apparatus is used to perform a liquid processing such as, for example, a cleaning process or an etching process for a substrate such as, for example, a semiconductor wafer and a liquid crystal substrate, with various kinds of processing liquids, and then, to perform a dry processing that removes the processing liquids remaining on the substrate.
In the substrate processing apparatus, a phenomenon called a substrate surface pattern collapse occurs in which the pattern of the substrate surface collapses by the action of the surface tension of the processing liquid remaining on the substrate during the dry processing. The pattern collapse occurs as the aspect ratio becomes higher according to the miniaturization of the pattern a substrate surface such as, for example, an etching mask pattern and a circuit pattern formed on the substrate surface.
In the conventional substrate processing apparatus, a substrate is processed with a processing liquid using a substrate liquid processing device, and thereafter, the substrate is subjected to a dry processing using a substrate dry processing device by substituting the processing liquid attached to the surface of the substrate with a substrate processing fluid in a supercritical state (carbon dioxide etc.) and then removing the supercritical fluid from the surface of the substrate.
In the substrate processing apparatus in which the dry processing is performed in the supercritical state, a fluid supply source that supplies the substrate processing fluid in a gas state and a processing chamber that processes the substrate are connected with each other by a supplying path, and a booster mechanism (pump) is installed in the middle portion of the supplying path to boost and deliver the substrate processing fluid into a predetermined pressure.
In the substrate processing apparatus, the substrate processing fluid supplied from the fluid supply source is boosted to a pressure to become a supercritical state by the booster mechanism, and then is supplied to the processing chamber, thereby performing the dry processing for the substrate using the substrate processing fluid in the supercritical state.
However, in the conventional substrate processing apparatus, since the substrate processing fluid is supplied to the processing chamber after the booster mechanism installed on the supplying path boosts the fluid, there is a concern that particles such as a dust which is generated by the booster mechanism when the substrate processing fluid passes the booster mechanism may be mixed into the substrate processing fluid.
Specifically, in the conventional substrate processing apparatus, since the substrate processing fluid always passes the booster mechanism when the substrate processing fluid is supplied to the processing chamber, there is a concern that the frequency where the particles are mixed into the substrate processing fluid may be increased and the substrate surface may be contaminated by the mixed particles. See, for example, Japanese Patent Laid-Open Publication No. 2008-66495.
Meanwhile, the process of manufacturing a semiconductor device in which a stack structure of an integrated circuit is formed on the surface of a substrate, such as a semiconductor wafer (hereinafter, a wafer) includes a liquid processing that processes the wafer surface using a cleaning liquid such as, for example, a chemical solution to remove minute dusts or native oxide layers on the wafer surface.
As the semiconductor devices are becoming highly integrated, there is a concern that a phenomenon called a pattern collapse occurs when the liquid attached to the wafer surface is removed in the liquid processing process. The pattern collapse is a phenomenon in which the balance of the surface tension horizontally pulling the convex portion is lost, and, as a result, the convex portions fall down toward the side where more liquids remain at the time of drying the remaining liquids on the wafer surface, as the liquids remaining at the left and right sides of the convex portion of concave and convex portions forming a pattern are unevenly dried.
As for a technique which removes the remaining liquids on the wafer surface while preventing the pattern collapse from being occurred, a method is known for using a fluid in a supercritical state or a subcritical state (hereinafter, collectively referred to as a high-pressure state). The viscosity of the fluid in the high-pressure state (high-pressure fluid) is lower than a liquid while the ability to dissolve the fluid is higher than the liquid. Further, there is no interface between the high-pressure fluid and a liquid or a gas which is in equilibrium state. Therefore, the liquid attached to the wafer surface is substituted with the high-pressure fluid, and thereafter, when the high-pressure fluid is changed to a gas state, the liquid may be dried without being affected by the surface tension.
For example, Japanese Patent Laid-Open Publication No. 2006-294662 (see, e.g., paragraphs [0028], [0036]-[0040], and FIG. 1) discloses a technology in which a liquid carbon dioxide is introduced into a high pressure chamber accommodating a substrate. The introduced liquid carbon dioxide is made to a supercritical state by being heated within the high-pressure chamber, and substitutes the liquid attached to the surface of the substrate. Here, in a supplying path through which the liquid carbon dioxide supplied to the high-pressure chamber flows, a filter is installed to prevent the liquid carbon dioxide from carrying the particles (foreign matters) from a vessel in which the liquid carbon dioxide is stored.
However, since the substrate is carried into the high-pressure chamber under the atmospheric pressure and then the supply of the liquid carbon dioxide is initiated, the pressure within the supplying path having the filter is greatly changed from the atmospheric pressure to a pressure where the carbon dioxide at the room temperature may be maintained to a liquid state (7.5 MPa in the case of Japanese Patent Laid-Open Publication No. 2006-294662). Further, the carbon dioxide passes the filter in a gas state during a period where the pressure within the supplying path is low and may become a liquid state as the pressure within the supplying path is increased. Therefore, the viscosity or density of the fluid that passes the filter may be greatly changed. As a result, there is a concern that the particles collected when the fluid passes the filter in a gas state are discharged as the fluid that passes the filter is changed to a liquid state, and introduced to the high-pressure chamber to contaminate the substrate.